Growing plants require water, oxygen and potentially other gases to support their life cycle. The water for most crops is derived from interstices in soil, which obtain it from rainfall or irrigation. Oxygen and other gases are obtained from the interstices, either from atmospheric gases which have migrated into the soil or from water in which the gases are dissolved. Although many gases can be beneficial to various crops, oxygen is one of the more important ones, and hence it will be dealt with specifically in this discussion, but this invention is not to be limited to the beneficial affects of oxygen only.
Generally, the concentration of oxygen or other gases in irrigation water is limited to that which is dissolved in accordance with Henry's Law. This is adequate for growth of crops. Farmers and growers of plants are fully aware of the range of wetness that a plant can tolerate. If the soil is maintained too wet for a substantial length of time, it will partially suffocate the microbial activity necessary for plant food conversion for plant uptake. It will, in effect drown. Too long a dry period will result in a lack of moisture to support plant transpiration even though there is plenty of oxygen in the soil.
Accordingly, with present practices, a plant grows best when it is alternately wetted and permitted to approach dryness. The grower attempts to provide adequate moisture and adequate oxygen to support varying transpiration ratios due to fluctuating weather conditions. Commercial intensive agricultural practice supplies oxygen as a function of the correct supply of oxygen dissolved in water, and as a function of air which is drawn into the soil as water is withdrawn from the interstitial spaces in the soil. However these sources can be quite variable. Well water, for example, tends to have less dissolved oxygen, and often contains undesirable other gases. The oxygen content in water supplied in ditches and furrows can vary depending on water temperatures and ambient conditions.
It is an object of this invention to control and to improve the supply of oxygen to the soil, and thereby improve the growth of the plant or crop. The terms "plant" and "crop" are used interchangeably herein.
This is a fundamental problem, and efforts have been made and suggested to improve the oxygen supply by aerating irrigation water. This can indeed increase the oxygen concentration in the water, but it does not address the issue of what gas content actually reaches all plants in an area of significant size. Previous efforts have achieved some disappointingly limited improvement. For example they have not provided an optimal increase in production by weight, uniform improvement over a substantial area, or significant advancement of maturity of the plants. Their small improvement has been commercially insignificant.
This invention does provide these improvements. For example, adjacent plots of land near Bakersfield, California were planted with bell pepper plants spaced about 12-14 inches apart, along raised rows about 620 feet long between furrows spaced about 40 inches apart. A test plot was prepared according to this invention, as will be described below. The control plot was planted the same way, with an identical irrigation system but without the air supply of this invention. The systems were operated identically.
The results were surprisingly and unpredictably favorable. For example, it was found that the peppers reached a given point of maturity with this invention about one week sooner than peppers in the control plot. This was confirmed by observing the presence of a larger proportion of red peppers to green peppers in the test plot sooner than in the control plot. This is not a small matter. Especially at the start of a season, the earlier produce commands immediate purchase and at a premium price. This premium goes straight to the bottom line as profit. In addition an increase in production in weight of crops over the full season of about 5.6% over the control plot was noted, which also is a direct profit from this invention.
Because this invention's effects are substantially uniform over the entire field, maximum production from a plot of significant size can be anticipated. While bell peppers are given as an example of the results of using this invention, other crops may expect beneficial results, also.
As a further advantage, the plants are less stressed while growing and producing. The average stress index of the control plot for the season was about -5.52, while the test plots had an index of about -5.76. A larger negative number is the better.
It is an object of this invention to provide a practical means to beneficiate the soil for the above purpose. By the term "beneficiate" is meant addition of a substance to improve the soil's microbial activity for better plant food uptake as a total body by the injection of air/oxygen into the vital root zone area of the plant including moisture for the intended purpose. It is not used in the sense of the addition of a chemical such as gypsum or fertilizer which is used to change the chemical constituents of the soil itself.